This gull was seen at Fort Worth, TX on March 17, 1998. The
bird disappeared within 1 minute of being found, and was never
seen again. It may be just an odd smithsonianus Herring
Gull, but it shows many features of Caspian Yellow-legged Gull
Larus (argentatus) cachinnans. Of special interest are
the long legs, long primary projection, dark smudge on the lower
flanks above the legs, and the white central belly (and undertail
coverts) - all strong features of 1st-basic L. (a.) cachinnans.
It would be educational to know how often these features combine
in 1st-basic L. a. smithsonianus. Most references indicate
that cachinnans would never be as dark on the underwing
coverts as is this bird - but Garner and Quinn (British Birds
vol. 90 numbers 1-2; page 54) offer the tantalizing prospect that
some can resemble michahellis in this regard.
In-the-field views were brief, and the only noted supplement to the photos is that the tail was not completely dark - the bases of the outer retrices were starkly white (with a little dark marking) - this is just visible in a couple of the photos.
Please send comments about this bird to the webmaster. The only modification to the photos has been some lightening and mild sharpening - no selective editing or other image manipulation:
The pic above is from Bahrain in early March by Howard King, and is presumed to be barabensis (keep in mind Howard's warning that the harsh light has exaggerated the dark tones) - compare this bird carefully to the image above it from Fort Worth...
Below is a modified version of the photo to the right; the gap between the odd gull and the RBGU has been removed to allow a better size comparison
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